Japanese entertainer in bondage is handmaiden (6)
I believe the answer is:
geisha
'japanese entertainer' is the definition.
(I've seen this before)
'in bondage is handmaiden' is the wordplay.
'in' indicates a hidden word.
'GEISHA' is hidden within 'bondage is handmaiden'.
(Other definitions for geisha that I've seen before include "Japanese hostess trained to entertain men" , "Professional female companion in Japan" , "Jap. hostess" , "Japanese woman trained to be a male companion" , "Female escort" .)